using a different aftercooler

[scdyne]

This is a very good question that really gets to the point when talking about the differences between centrifugal superchargers, eBay turbos and brand name Turbos.
First of all there are a few different types of bearings and in our case there are fluid bearings and ball bearings. There are also a few different types of drives from direct, on a turbo, to gears or cog and belt, for most centrifugal superchargers, and planetary drive for the Rotrex supercharger. Each of these bearing systems are designed to reduce heat and friction (which are complementary to each other) by taking advantage of oil viscosity. Additionally some higher end turbo's also use water to help cool the bearing housing to help maintain proper oil temperature and viscosity.

http://auto.howstuffworks.com/turbo.htm - This is a good generalization of turbochargers and link to ball bearings.

When all is said and done the primary limiting factor for impeller speed is the bearing design.

Fluid bearings are nothing more than a housing that contains an oil layer between a hardened steel shaft and brass babbitted housing. Oil viscosity directly separates the two materials from coming in contact and once viscosity breaks down due to heat, contaminates, or impeller shock failure soon fallows. Generally impeller speeds run around 120,000 RPM with these systems, but can go higher with high precision hardware, water cooling, and the right oil. (READ: brand name Garrett, Turbonetics, etc- NOT OBX and other Chinese made knock-offs) Precision hardware, exacting tolerances and proprietary aerospace grade treatments are the KEY to a quality Turbocharger.


Precision Ball Bearings use high quality hardened balls housed in their own hardened casings (inner/outer). Some use internal lubrication (Powerdyne Superchargers) and others use provided oil. The inner race is pressed to the impeller and the outer race is pressed to the main housing with only the ball bearings coming in contact with the housing at a single ball point - that is in fact separated by the oil. Loads in all directions are controlled by the bearing design and oil viscosity producing less friction. This along with lower mass impeller shafts, composite impeller materials and better cooling impellers can reach speeds of 300,000 rpm. Generally with most turbo's impeller speeds are around 200,000 rpm, but as pointed out other systems exceed 500K RPM.
Side note - Dental tools use ceramic ball bearings with 'ceramic balls', which can withstand temperatures of 250 deg C static (cleaning) and 100 deg C during operation. I think they are water lubricated or internally lubricated with special bearing grease.

In the case of Centrifugal Superchargers the limits are not always the bearings (many Powerdyne owners will disagree-incorrectly) it's the fact that the transmission needed to get from engine RPM to impeller RPM would need to be very large for impeller speeds beyond 60,000 RPM. Most S/C's are designed for voulme instead of pressure to over come the lack of impeller speeds and as a result are less efficient. Vortech, Paxton and Procharger all use normal high speed precision metal ball bearings with any number of oil sources, and in extreme cases use ceramic. Powerdyne being a dry blower uses internally lubricated bearings that tend to blow out due more to heat than impeller speeds- however they are limited to around 50,000 rpm because they are internally lubricated. Ceramic upgrades, special cooling of the housing and proper system design on Powerdyne blowers have achieved much higher impeller speeds and efficiency, but nothing close to that of a Turbo.

Rotrex trumped them all with a planetary drive transmission that can achieve turbo impeller speeds. They too use ball bearings, but the whole transmission is a friction drive system that resides on a thin layer of oil. In this case it's the friction that drives the system and can multiply crank rpm's as much as 12 times. Combined with external pulleys 120,000 rpm impeller speeds are possible.

more later.. I have to eat breakfast..

[rfmarz@frontiernet]

Thank you scdyne! That was a great explanation of the various types and lubrication methods of bearings that we take soooo forgranted (until they fail).
Did you ever wonder; once you have a given bit of information, what do you do with it?

[MadMaxedAtom]

"Did you ever wonder; once you have a given bit of information, what do you do with it?"

If you're smart,you remember it for future use...

[bolus]

New intercooler showed up today from TTS
[img width=450 height=600]http://bolus.shackspace.com/atom/turbo/Turbo1.jpg[/img]
[img width=450 height=600]http://bolus.shackspace.com/atom/turbo/Turbo2.jpg[/img]

[Gage]

 

[CalScot]

Looks familiar! I have a good idea where you can shove that thing and with a few other bit's & pieces, get enough HP to scare you shitless. 
You have taken the first step to the DARK SIDE my son! 

[bolus]

I dont know if they did it or I did it.  I ripped it out of the box with a lot of excitement so it was probably me.  Nothing a radiator comb wont fix though. 

[DarthChicken]

this is gonna be fun 

[MadMaxedAtom]

[scdyne]

wow, after going to Motor4Toys and seeing the 2 Atom's there I really don't know if there is enough space for an S/C. One side has the frame on bottom and suspension on top and the other side has a catch-can and exhaust in the way. Without cutting the heck out of the engine cover I don't see any reasonable place to install a centrifugal supercharger. And it would have to be a Rotrex because there is no way an old school Powerdyne, vortech, ATI unit would fit in the limited space available. Short of some major replacement of engine parts and cutting of the engine cover I just don't see the space. In my opinion it may be easier to install a turbo or swap out the engine for a LNF rather than strapping a centrifugal S/C to it.
Mind you there is no doubt I could do a S/C install, but it would be very cost prohibitive.